The action of aldosterone on target tissue is via the induction of RNA and protein synthesis. The first step in this process is binding of steroid to a cytoplasmic receptor. The concept of an allosteric receptor, one which exists in two states, was suggested on the basis of work with aldosterone and an aldosterone-antagonist, spirolactone. In this model, agonists bound to the receptor have high affinity for nuclear target sites while antagonists bound to the same receptor have low affinity for these sites, and thereby antagonize the action of aldosterone. Very little is known about the nature of the chromatin binding site. This study attempts to isolate this site and study the interaction of receptor with its chromatin target. The importance of these studies lies in a need to know how steroid hormones affect gene regulation in normal and neoplastic tissues.